1. Field of the Invention
This invention relates to a semiconductor diode, more particularly to a semiconductor diode that is capable of detecting hydrogen at high temperatures.
2. Description of the Related Art
In co-pending U.S. patent application Ser. No. 10/725,801, the applicant disclosed a semiconductor diode with hydrogen detection capability. The semiconductor diode includes: a semiconductor substrate; a doped semiconductor active layer formed on the substrate and made from a compound having the formula XYZ, in which X is a Group m element, Y is another Group III element different from X, and Z is a Group V element; an ohmic contact layer formed on the active layer; and a Schottky barrier contact layer formed on the active layer so as to provide a Schottky barrier therebetween. The Schottky barrier contact layer is made from a metal that is capable of dissociating a hydrogen molecule into hydrogen atoms. The active layer is preferably made from n-type InGaP or AlxGa1-xAs so as to impart the semiconductor diode with a capability of detecting hydrogen at high temperatures.
However, due to a relatively large difference in surface property between the ohmic contact and the active layer, the contact therebetween is relatively poor, which results in an increase in the electrical resistance of the semiconductor diode.
The whole disclosure of the co-pending U.S. patent application Ser. No. 10/725,801 is incorporated herein by reference.